The fuel injection system admits a fuel, such as gasoline, into an internal combustion engine. Different types of fuel injection system may be divided generally into port fuel injection and direct injection. Port fuel injection injects fuel into a runner of an air intake manifold that is connected to a cylinder intake port of an engine cylinder. Direct injection injects fuel directly into a combustion chamber of a piston of an engine cylinder, typically during a compression stroke of the piston.
Direct injection typically has the advantage of greater control and greater precision of fuel charge to the combustion chamber under various operating conditions. This then results in better fuel economy as well as lower emissions. Moreover, the direct injection allows higher compression ratios, which enables delivery of higher performance with lower fuel consumption as compared to other fuel injection systems. High-pressure direct injection fuel injectors often use inwardly opening valves in conjunction with solenoid actuation.